A well often has restrictions, such as nipples, no-goes or patches, and the inner diameter at this restriction therefore defines the maximum outer diameter of an intervention tool intervening the well to perform an operation. Cleaning a lower part of the well requires a flexible brush capable of bending its brushing arms when passing the restriction. Furthermore, wells sometimes have a cased part and an un-cased part, the un-cased part also being referred to as an open hole well. In order to clean the open hole part, the brush or similar cleaning tool also has to be flexible in order to pass the narrow cased part. However, it has proved to be difficult for known cleaning brushes to clean certain types of scale which could more easily be removed by a somewhat flexible brush.